Polymeric thiazole fog stabilizers for photographic emulsions

ABSTRACT

POLYMER THIAZOLES CONTAINING THIAZOLE GROUPS EITHER INCORPORATED INTO THE POLYMER CHAIN OR APPENDED TO THE POLYMER BACKBONE AND PHOTOGRAPHIC SILVER HALIDE EMULSIONS OR PHOTOGRAPHIC ELEMENTS CONTAINING FOG-STABILIZING AMOUNTS OF SUCH POLYMERIC THIAZOLES.

United States Patent 01 ace US. Cl. 96-109 19 Claims ABSTRACT OF THEDISCLOSURE Polymeric thiazoles containing thiazole groups eitherincorporated into the polymer chain or appended to the polymer backboneand photographic silver halide emulsions or photographic elementscontaining fog-stabilizing amounts of such polymeric thiazoles.

BACKGROUND OF THE INVENTION Field of the invention This inventionrelates to new polymers which are useful as improved antifoggants andstabilizers for photographic elements and to photographic silver halideemulsions containing such polymers as antifoggants and stabilizerstherein.

Description of the prior art During development of a silver halideemulsion, small amounts of silver halide are reduced to metallic silverregardless of whether or not they have been exposed. This reduction ofsilver ion produces a background fog which is more specifically referredto as chemical fog.

Chemical fog, apparent in most silver halide systems, has been reducedby prior art methods of processing exposed silver halide material in thepresence of compounds which restrict development of unexposed silverhalide. Such compounds can be incorporated in the silver halide emulsionor in the processing solutions for developing such silver halideemulsions. Compounds which have been found to have a chemical foginhibiting effect on emulsions which have been subjected to hightemperature and high humidity conditions are referred to as emulsionstabilizers. On the other hand, compounds which have been found to havechemical fog inhibiting elfects on emulsions which have not been exposedto adverse storage conditions are referred to as antifoggants. Althougha large number of emulsion stabilizers and antifoggants have been usedin the prior art, many of these compounds cause undesirable losses inemulsion speed and contrast and others lack adequate compatibility withemulsion gelatin.

SUMMARY OF THE INVENTION According to one embodiment of this invention,there is provided a new class of polymers which are particularly usefulas photographic antifoggants and stabilizers. These new polymers containrecurring groups having the formula wherein y is or 1, the radical A isS or NH- and X is a thiazole group. The thiazole groups constitute atleast 30% by weight of the polymer and are monovalent when appended tothe polymeric backbone and divalent when incorporated into the polymericbackbone.

According to another embodiment of this invention, there is incorporatedinto the silver halide emulsion of a photographic element or in a layercontiguous to the silver halide emulsion, a fog-stabilizing amount of apoly- 3,598,599 Patented Aug. 10, 1971 mer containing recurring thiazolegroups. The polymer stabilizes the emulsion against fog when the driedemulsion has been subjected to a prolonged high humidity and temperatureincubation period without adversely affecting other sensitometricproperties. It is an advantage of high molecular weight materials, e.g.,polymers, that they remain relatively immobile when incorporated intoparticular layers of a photographic element.

DESCRIPTION OF THE PREFERRED EMBODIMENTS One preferred group of polymersin accordance with this invention have the thiazole group incorporatedinto the polymer chain or backbone. These polymers contain repeatingsegments having the formula wherein z is an integer of 3 to 8, and R isselected from the group consisting of hydrogen atoms, alkyl (e.g.,methyl, ethyl, butyl), and phenyl radicals. Such polymers can beprepared by reacting a diaminothiazole with a dicarboxylic dihalide inan inert solvent.

Another preferred group of polymers have the thiazole groups appended tothe polymeric backbone. These polymers contain repeating segments havingthe formula and radicals; and each R is selected from the groupconsisting of hydroxy radicals and thioazolyl radicals having theformulae:

at least 25 percent of the total R radicals being said thiazolylradicals. Such polymers can be prepared by reacting a thiazole which issubstituted with a functional group, such as an amino or sulfhydrylgroup, with a polymer containing reactive groups such as anhydride orester groups. The reaction can be conducted in the presence of sodiumcarbonate or sodium hydroxide. When the intermediate polymer is onewhich contains anhydride groups, such as copoly(styrene-maleicanhydride) or poly(arcylic anhydride), at least half of the A R groupsin the above formula will be carboxy radicals. Intermediate polymershaving intrinsic viscositties of up to about 1.5 are preferred.

The polymeric thiazoles of this invention can be incorporated into asilver halide emulsion of a photographic element or in a layercontiguous to the silver halide emulsion in any amount which willstabilize the silver halide emulsion against fog. In general, aconcentration of the polymeric thiazole in an amount of from about 0.10to about 50.0, preferably about 0.12 to about 19.0 grams per mole ofsilver in the silver halide emulsion can be used with good results.

The preparation of photographic silver halide emulsions such as aresuitably stabilized with a polymeric thiazole typically involves threeseparate operations: (1) emulsification and digestion of silver halide,(2) the freeing of the emulsion of excess water-soluble salts, suitablyby washing with water, and (3) the second digestion or after-ripening toobtain increased emulsion speed or sensitivity. (Mees, The Theory of thePhotographic Process, 1954.) The polymeric thiazole can be added to theemulsion before the final digestion or after-ripening or it can be addedimmediately prior to the coating.

The silver halide emulsion of a photographic element containing theantifoggants of this invention can contain conventional addenda such asgelatin plasticizers, coating aids, and hardeners such as aldehydehardeners, e.g., form aldehyde, mucochloric acid, glutaraldehydebis(sodium bisulfite), maleic dialdehyde, aziridines, dioxanederivatives and oxypolysaccharides. Spectral sensitizers which can beused are the cyanines, merocyanines, complex (trinuclear) cyanines,complex (trinuclear) merocyanines, styryls, and hemicyanines.Sensitizing dyes useful in sensitizing such emulsions are described, forexample, in U.S. Pats. 2,526,632 of Brooker and White issued Oct. 24,1950, and 2,503,776 of Sprague issued Apr. 11, 1950. Developing agentscan also be incorporated into the silver halide emulsion if desired orcan be contained in a con tiguous layer. Various silver salts can beused as the sensitive salt such as silver bromide, silver iodide, silverchloride, or mixed silver halides such as silver chlorobromide or silverbromoiodide. The silver halides used can be those which form latentimages predominantly on the surface of the silver halide grains or thosewhich form latent images inside the silver halide crystals such asdescribed in US. Pat. 2,592,250 of Davey and Knott issued Apr. 8, 1952.

The silver halide emulsion layer of a photographic element containingthe antifoggants of the invention can contain any of the hydrophilic,water-permeable hiding materials suitable for this purpose. Suitablematerials include gelatin, colloidal albumin, polyvinyl compounds,celluose derivatives, acrylamide polymers, etc. Mixtures of thesebinding agents can also be used. The binding agents for the emulsionlayer of the photographic element can also contain dispersed polymerizedvinyl compounds. Such compounds are disclosed, for example, in US. Pats.3,142,568 of Nottorf issued July 28, 1964; 3,193,386 of White issuedJuly 6, 1965; 3,062,674 of Houck, Smith and Yudelson issued Nov. 6,1962; and

4 3,220,844 of Houck, Smith and Yudelson issued Nov. 30, 1965; andinclude the water-insoluble polymers of alkyl acrylates andmethacrylates, acrylic acid, sulfoalkyl acrylates or methacrylates andthe like.

The silver halide emulsion of a photographic element containing theantifoggants of the invention can be coated on a wide variety ofsupports. Typical supports are cellulose nitrate film, cellulose esterfilm, polyvinyl acetal film, polystyrene film, poly (ethyleneterephthalate) film and related films or resinous materials as well asglass, paper, metal and the like. Supports such as paper which arecoated with a-olefin polymers, particularly polymers of a-olefinscontaining two or more carbon atoms, as exemplified by polyethylene,polypropylene, ethylene butene copolymers and the like can also beemployed.

The speed of the photographic emulsions containing the antifoggants ofthe invention can be further enhanced by including in the emulsions avariety of hydrophilic colloids such as carboxymethyl protein of thetype described in US. Pat. 3,011,890 of Gates, Jr., Miller and Kollerissued Dec. 5, 1961, and polysaccharides of the type described inCanadian Pat. 635,206 of Koller and Russell issued Jan. 23, 1962.

Photographic emulsions containing the antifoggants of the invention canalso contain speed-increasing compounds such as quaternary ammoniumcompounds, polyethylene glycols .or thioethers.

Photographic elements containing the antifoggants of the instantinvention can be used in various kinds of photographic systems. Inaddition to being useful in X-ray and other non-optically sensitizedsystems, they can also be used in orthochromatic, panchromatic andinfrared sensitive systems. The sensitizing addenda can be added tophotographic systems before or after any sensitizing dyes which areused.

Silver halide emulsions containing the antifoggants of the invention canbe used in color photography, for example, emulsions containingcolor-forming couplers or emulsions to be developed by solutionscontaining couplers or other color-generating materials, emulsions ofthe mixed-packet type such as described in US. Pat. 2,698,794 ofGodowsky issued Jan. 4, 1955; in silver dye-bleach systems; andemulsions of the mixed-grain type such as described in US. Pat.2,592,243 of Carroll and Hanson issued Apr. 8, 1952.

Silver halide emulsions containing the antifoggants of the invention canbe sensitized using any of the wellknown techniques in emulsion making,for example, by digesting with naturally active gelatin or varioussulfur, selenium, tellurium compounds and/ or gold compounds. Theemulsions can also be sensitized with salts of noble metals of GroupVIII of the Periodic Table which have an atomic weight greater than 100.

Silver halide emulsions containing the antifoggants of the invention canbe used in diffusion transfer processes which utilize the undevelopedsilver halide in non-image areas of the negative to form a positive bydissolving the undeveloped silver halide and precipitating it on asilver layer in close proximity to the original silver halide emulsionlayer. Such processes are described in US. Pats. 2,352,014 of Rottissued June 20, 1944; 2,543,181 of Land issued Feb. 27, 1951; and3,020,155 of Yackel, Yutzy, Foster and Rasch issued Feb. 6, 1962. Theemulsions can also be used in diffusion transfer color processes whichutilize a diffusion transfer of an imagewise distribution of developer,coupler or dye, from a light-sensitive layer to a second layer, whilethe two layers are in close proximity to one another. Silver halideemulsions containing the antifoggants of the invention can be processedin stabilization processes. such as the ones described in US. Pat.2,614,927 of Broughton and Woodward issued Oct. 21, 1952, and asdescribed in the article Stabilization Processing of Films and Papers byH. D. Russell, E. C. Yackel and I. S. Bruce in P.S.A. Journal,Photographic Science and Technique, Volume 16B, October 1950.

The antifogging agents of this invention can be incorporated toadvantage during manufacture in silver halide emulsions representing thevariations described above. Moreover, fog control in binderless silverhalide films prepared by vapor deposition of silver halide on a suitablesupport can be achieved by coating the antifogging agents of theinvention over the vapor deposited layer of silver halide.

Combinations of all the above-mentioned addenda can be used if desired.

The following examples illustrate the best modes contemplated forcarrying out this invention; although it will be understood that theseexamples are included merely for purposes of illustration and are notintended to limit the scope of the invention.

EXAMPLE 1 To a mixture of 2,4-diamino-5-phenylthiazole monohydrobromide(25.5 grams, 0.094 mole) and triethylamine (31 grams, 0.307 mole) in 200milliliters of dimethylformamide is added in one portion adipyl chloride(17.2 grams, 0.094 mole) with rapid stirring under nitrogen at roomtemperature. The reaction is allowed to run under ambient conditions for24 hours. The product is precipitated by pouring the reaction mixtureinto 2-3 liters of water with stirring. The product is filtered, washedaagin with water, and dried in a vacuum oven at 40 C. overnight. Yieldof light yellow solid is 20.5 grams.

Analysis.-Found (percent): C, 58.0; H, 5.2; N, 14.0; S, 11.8; CI, 0.5.

The inherent viscosity in dimethylformamide is 0.06. The productconsists essentially of repeating segments having the formula Theproduct is dissolved in dimethylformamide/water (2/1), pH adjusted to6.3 with percent sodium hydroxide, and subjected to photographic testingas described hereinafter.

EXAMPLE 2 To a solution of copoly(ethylene-maleic anhydride) having aninherent viscosity in dimethylformamide of 0.82 (12.6 grams, 0.1 mole)in 200 milliliters of dimethylformamide is added 2-aminobenzothiazole(15.0 grams, 0.1 mole). The reaction mixture is stirred under nitrogenfor 4 hours at 75 C. The entire content is poured into 2-3 liters ofdiethyl ether with stirring. The supernatant ether is decanted and theprecipitate is washed with water and dried in a vacuum oven at 40 C.overnight. The yield of light tan solid is 22.5 grams. After drying, theproduct is again washed with water, followed by ether and re-dried. Thefinal yield of light tan solid is 16 grams.

Analysis-Found (percent): C, 54.0; H, 4.8; N, 6.2; S, 6.8. Theanalytical results for nitrogen and sulfur are consistent with theproduct containing about 60 percent of the theoretical amount of thebenzothiazole system off the polymer chain. The product containsrepeating segments having the formula The product is suspended in waterand dissolved by adding 10 percent sodium hydroxide. The solution, pH:6.2, 1s subjected to photographic testing as hereinafter described.

EXAMPLE 3 The process of Example 2 is repeated substituting for thecopoly(ethylene-maleic anhydride) an equimolar amount of poly(acrylicanhydride) having an inherent viscosity in dimethylformamide of 0.31.The product contains recurring segments having the formulae and l j S im HN wherein the ratio of the values of m to n is about 5:3. Analysis ofthe product for nitrogen and sulfur indicates that the product containsabout percent of the theoretical amount of benzothiazole groups off thepolymer chain.

EXAMPLE 4 Analysis of the product for nitrogen and sulfur indicates thatthe product contains about percent of the theoretical amount of2-mercapto-6-aminobenzothiazole groups off the polymer chain.

EXAMPLE 5 The process of Example 3 is repeated substituting for the2-aminobenzothiazole an equimolar amount of 2-mercapto-6-aminobenzothiazole and using a poly(acrylic anhydride) havingan inherent viscosity in dimethylformamide of 0.79. The product containsrecurring segments having the formulae wherein the ratio of the valuesof m and n is about 2:1. Analysis of the product for nitrogen and sulfurindicates that the product contains about 70 percent of the theoreticalamount of Z-mercapto-6-aminobenzothiazole groups off the polymer chain.

EXAMPLE 6 The process of Example 3 is repeated substituting for theZ-aminobenzothiazole an equimolar amount of 2- aminothiazole and using apoly(acrylic anhydride) having an inherent viscosity indimethylformamide of 0.23. The product contains recurring segmentshaving the formulae.

and

wherein the ratio of the values of m and n is about 4:3. Analysis of theproduct for nitrogen and sulfur indicates that the product containsabout 85 percent of the theoretical amount of 2-aminothiazole groups offthe polymer chain.

7 EXAMPLE 7 The process of Example 6 is repeated substituting for thepoly(acrylic anhydride) an equimolar amount of copoly(styrene-maleicanhydride) having an inherent viscosity in dimethylformamide of 1.37.The product contains repeating segments having the formula Analysis ofthe product for nitrogen and sulfur indicates that the product containsabout 82 percent of the theoretical amount of the 2-amin0thiazo1e groupsoff the polymer chain.

EXAMPLE 8 The process of Eample 2 is repeated substituting for the2-aminobenzoth'iazole an equimolar amount of 2-amino-4-(4-biphenylyl)triazole. The product contains repeating segmentshaving the formula HO HN Analysis of the product for nitrogen and sulfurindicates that the product contains about 75 percent of the theoreticalamount of Z-amino-4-p-diphenylthiazole groups off the polymer chain.

EXAMPLE 9 Vinyl acetate is polymerized in refluxing methanol solution inthe presence of an equimolar amount of chloroform using about 3 percentby weight of monomer of 2,2'-azobis(Z-methylpropionitrile) as catalyst.The polymerization is allowed to run for 48 hours at 70 C. undernitrogen. The product is obtained as a tacky, light yellow solid byevaporating oil the solvent and washing the residue with ligroine. Theproduct is further purified by dissolving it in a small volume ofacetone and precipitating into ligroine. After drying, the yield oftacky solid is about 4050 percent of the theoretical yield. The inherentviscosity of the product in acetone is 0.13 and the molecular weight isestimated on the basis of chlorine analysis to be between 3000 and 4000.This product is hydrolyzed using sodium hydroxide in methanol to givepoly(vinyl alcohol).

Low molecular weight poly(vinyl alcohol) prepared as described above (22grams, about 0.05 mole) and chloroacetic anhydride (90 grams, 0.525mole) are heated together in 1000 milliliters of refluxing1,2-dichloroethane under nitrogen for 4 to hours. The reaction mixtureis then poured into 2-3 liters of methanol. The precipitated product iswashed with additional methanol and the resulting gummy solid is driedin a vacuum oven overnight. The yield of yellow-tan, flaky solid is 21grams.

Analysis.Calcd. (percent): Cl, 29.4. Found (percent): CI, 26.3.

The calculated chlorine analysis is for the polymer repeating unitwithout end-groups. The chlorine analysis indicates about 8590 percentreaction to give the chloroacetate product. Concentration of the motherliquors followed by washing with diethyl ether and reprecipitating froma small amount of acetone with ligroine yielded another 14 grams ofgummy product after drying. The product is low molecular weightpoly(vinyl chloroacetate).

To a solution of poly(vinyl chloroacetate) prepared as described above(12.0 grams, 0.1 mole) in 200 milliters of dimethylformamide are addedZ-mercaptobenzothiazole (16.7 grams, 0.1 mole) and sodium carbonate (5.3grams, 0.05 mole). The mixture is heated at 70 C.

for 24 hours under nitrogen with stirring. The reaction mixture ispoured into 2-3 liters of Water with stirring and filtered. The solid isWashed very well with methanol, filtered, and dried in a vacuum oven at40 C. overnight. The product, 14 grams, is a light tan solid.

Analysis.Found (percent): C, 52.2; H, 4.5; N, 3.5; S, 18.9; C1, 5.1.

The analytical results for nitrogen and sulfur are consistent with aproduct containing about 60-70 percent of the theoretical amount of thebenzothiazole system off the polymer chain. The product containsrepeating segments having the formula The product is dissolved in a 1:1mixture of dimethylformamide and acetone and the solution is subjectedto photographic testing as hereinafter described.

EXAMPLE 1O Polyvinyl alcohol having an inherent viscosity in water of0.4 is treated with chloroacetic anhydride as described in Example 9 toobtain poly(vinyl chloroacetate) having a chlorine content of 28.0%. Theproduct is then reacted with Z-mercaptobenzothiazole as described inExample 9. Analysis of the product for nitrogen and sulfur indicatesthat the product contains about 82 percent of the theoretical amount ofZ-mercaptobenzothiazole groups ofr th polymer chain. 1

EXAMPLE l1 Z-mercaptobenzothiazole (16.7 grams, 0.1 mole) and sodiumhydroxide (4.0 grams, 0.1 mole) are heated in 200 milliliters ofdimethylformamide for one hour at 75 C. under nitrogen.Copoly(ethylene-maleic anhydride) having an inherent viscosity indimethylformamide of 0.13 (12.6 grams, 0.1 mole) is added and themixture heated at 75 C. for 4 hours under nitrogen. The reaction mixtureis poured into 2-3 liters of acetone with stirring. The product isfiltered off and dried in a vacuum oven at 40 C. overnight. A purplishsolid (15 grams) is obtained. The dry solid is washed very well withmethanol and re-dried. Recovery of the product is 13 grams.

Analysis-Found (percent): C, 39.9; H, 4.4; N, 2.1; 2.6; 2.8; S, 2; Na,11.6.

The nitrogen analysis is consistent with a product containing about50-60 percent of the theoretical amount of the benzothiazole system offthe polymer chain. The product contains repeating segments having theformula The product is dissolved in water and the pH adjusted to 6.4 bythe addition of 10 percent aqueous sodium hydroxide. The resultingsolution is subjected to photographic testing as described hereinafter.

EXAMPLE 12 The process of Example 11 is repeated substituting for the2-mercaptobenzothiazole an equimolar amount of 2-rnercapto-6-nitrobenzothiazole. The product contains repeating segmentshaving the formula Analysis of the product for nitrogen and sulfurindicates that the product contains about 25 percent of the theoreticalamount of Z-mercapto-6-nitrobenzothiazole groups off the polymer chain.

and is terminated at one end thereof by H and on the other end by thegroup SCHCH OH.

EXAMPLE 15 EXAMPLE 13 2-aminobenzothiazole (9.0 grams, 0.06 mole) andvinylte (4.15 grams 0.06 mole) are allowed to react Low molecular wer htol hen l acr late havin a tsocyana molecular weight of aiapr xiiiia tely1060 and iermina t ed m 250 mllhhhters. anhydrous dlethyl ether P withZ-mercaptoethanol (14.6 grams, 0.1 mole) is dispefature under [Imogenfor hours a i solved in 200 milliliters of distilledN-methylpyrrolidone. minutes after the reactatits are mlxed Whlle begins2-aminothiazole (18 grams, 0.18 mole) is added and the toseparatifronzithz prevlously homogeneous reaptlon i reaction mixture isheated with stirring under nitrogen at i t t 6 en 0 the teale901 penodthe .Whlte F 160-170 C. for 24 hours. The reaction medium is homo- Hate1S filtered wafhed Wlth. ether and The yleld geneous and turns quitedark during the course of the E; mduct ;\I'vmy1 N 'benzothlazol'z'ylurea 18 11 grams t heating period. The product 15 prec1p1tated bypourlng the perceil c reaction mixture into 3 liters of distilled water.The pre- 15 19 ig i l ffg z ffi 5 g cipitate is then washed severaltimes with fresh quantities 3 N o perce of water to allow for removal ofany unreacted Z-aminot 'M R t t th thiazole, filtered and dried in avacuum overnight. The e a spec m are consls cm W 6 yield of tan solid isabout 17 grams. 'N 'beniothlazoliz'yl urea structute' Analysis Found(percenty C H N 16 20 N-vmyl-N -benb0th1aZol-2-yl urea 1s polymerized inS 19 4 refluxlng acetone with 1 percent 2,2-azobis-[2-methylpro- Thenitrogen and sulfur analyses are consistent with a plomtnle] fatalystfor 24 under. nitrogen T product wherein about 90 percent of the phenylester product preclpitates from solutlon as a whlle sol1d during groupshave reacted to give the thiazolyl-amide linkage. the course of i heaimg9 The Infrared .Spectrum of The product is dissolved indimethylformamide and 25 the pq cqnslstent wlth polymer; Structuretested as an antifoggant as described hereinafter. compnsmg repeatingSegments havmg the formula The product contains repeating segmentshaving the formula -CH2CH -CH2?H I N S 1 HN l NH- N and is terminated atone end thereof by H and on the other end thereof by the group SCH CHOH.

EXAMPLE 14 The polymerfis dissolved in dimethylformamide for testn as ananti 0 t. The process of EJFamPIe 13 is repiated usmg poly 4O 1 Each ofthe c iiiaounds prepared in Examples 1 to 15 5552221122 33? 3.222%:523E231? 332122.232; 4

b 1 f th than): in 1od1de emuls1on. For purposes of comparison, highspeed g m 0 d i a l P. d nd silver br0mo1od1de emuls1ons are alsoprepared lncoron O h no 13 Preclpl e a poratmg the hydrolysls productsof the intermediate polymet anolrat ert g z 5 N 12 8' mers used inExamples 5 and 11 i.e., polyacrylic acid Analyszs.-Found (percent). 5.3, H, obtained by hydrolysis of the polyacrylic anhydride nitro n andsulfur anal Ses indicate that about having an inherent viscosity indimethyltormamide of 0.79 85 95 f th h 1 t y h t d t andcopoly(ethylene-ma le1c ac1d) obta1ned by hydrolysis hp g a l l Yd r ffgh ave d 6 o ot copoly(ethy1ene-male1c anhydrlde) havmg an inherent f te 1 lazoy 3 g e Pro uct vlscosity in dimethylformamide of 0.13. Eachemulsion tams repeatmg segments havmgt e ormula sample is coated on acellulose acetate film support at a CH2CH coverage of 459 milligrams ofsilver and 1040 milligrams of gelatin per square foot. A sample of eachfilm coating is exposed on an intensity scale sensitometer, processedfor i five minutes in Kodak Developer DK-SO, fixed, washed and dried.The photographic results obtained from these 5 tests are listed in thetable below.

TABLE Incubation at 120 F. and 50% Fresh relative humidity for 2 weeksG. l R l. R 1. Compound of Example l g spee ii Gamma Fog spee d GammaFog 100 1.38 0. 11 33 0. s0 0. 74 so 1. 52 0. 10 so 1. 12 0. 20 97 1. 430. 14 63 1. 10 0. 29

TABLE Continued Incubation at 120 F. and 50% Fresh relative humidity for2 weeks G./rnole Rel. Rel.

Compound of Example Ag speed Gamma Fog speed Gamma Fog Polyacrylic acid18.0 110 1. 65 0. 35. 5 0. 85 1 0. 83 Copoly(ethylene maleic acid) 45. 0123 1. 62 0. 24 1 1. 0

1 l-week incubation instead of 2-week incubation.

The results in the above table show that the compounds of the inventionprevent the growth of incubation fog when incorporated in photographicemulsions but that polymers which do not contain the thiazole nucleusare either inert or cause fog in photographic emulsions.

Although the invention has been described in considerable detail withreference to certain embodiments thereof, it will be understood thatvariations and modifications can be effected without departing from thespirit and scope of the invention as described hereinabove and asdefined in the appended claims.

We claim:

1. A composition comprising a photographic silver halide emulsionstabilized against fog with a fog-stabilizing amount of a polymericthiazole containing repeating segments having the formula wherein thethiazole groups consititue at least by weight of said polymericthiazole.

4. A composition comprising a photographic silver halide emulsionstabilized against fog with a fog-stabilizing amount of a polymericthiazole containing repeating segments having the formula wherein at is0 or 1, and when x is 0, R is hydrogen, and when x is 1, R is hydrogenor phenyl; A is selected from the group consisting of radicals; and eachR is selected from the group consisting of hydroxy radicals andthiazolyl radicals having the formulae:

\S/ 7:9 are at least 25 percent of the total R radicals being saidthiazolyl radicals.

5. A composition as set forth in claim 4 wherein said repeating segmentshave the formula OH HILJ 6. A composition as set forth in claim 4.wherein said repeating segments have the formula Q) HJKEQQ 7. Acomposition as set forth in claim 4 wherein said repeating segments havethe formula 8. A composition as set forth in claim 4 wherein saidrepeating segments have the formula 9. A composition as set forth inclaim 4 wherein said repeating segments have the formula and wherein thepolymer is terminated on one end thereof by H and on the other endthereof by the group SCH CH OH.

10. A composition as set forth in claim 4 wherein said repeatingsegments have the formula and wherein the polymer is terminated on oneend thereof by -H and on the other end thereof by the group SCH CH OH.

11. A photographic element comprising a support coated with a silverhalide layer, said element stabilized against fog by a fog-stabilizingamount of a polymeric thiazole containing repeating segments having theformula N -Nn Time (CH1) Pr":-

wherein z is an integer of from 3 to 8, and R is hydrogen, alkyl, orphenyl, and wherein the thiazole groups constitute at least 30% byweight of said polymeric thiazole.

12. A photographic element comprising a support coated with a silverhalide layer, said element stabilized against fog by a fog-stabilizingamount of a polymeric thiazole containing repeating segments having theformula wherein the thiazole groups constitute at least 30% by weight ofsaid polymeric thiazole.

13'. A photographic element comprising a support coated with a silverhalide emulsion, said element stabilized against fog by afog-stabilizing amount of a polymeric thiazole containing repeatingsegments having the formulae at least 25 percent of the total R radicalsbeing said thiazolyl radicals.

14. A photographic element as set forth in claim 13, wherein saidrepeating segments have the formula DE EN 15. A photographic element asset forth in claim 13, wherein said repeating segments have the formula-CH2CHCHCH2 8 H0 HN- 16. A photographic element as set forth in claim13,

wherein said repeating segments have the formula CHzCHCHCHz 17. Aphotographic element as set forth in claim 13, wherein said repeatingsegments have the formula I l S 6 NO2 s 18. A photographic element asset forth in claim 13, wherein said repeating segments have the formulaCHzCH no N Hl and wherein the polymer is terminated on one end thereofby -H and on the other end thereof by the group SCH CH OH.

19. A photographic element as set forth in claim 13, wherein saidrepeating segments have the formula and wherein the polymer isterminated on one end thereof by H and on the other end thereof by thegroup -SCH CH OH.

US. Cl. X.R. 96-114

